1. Field of the Invention
The present invention relates to a flat type fluorescent lamp for use in a device such as a transparent type liquid crystal display, specifically for use as a back light thereof, in particular, where no memory is used therein.
2. Description of Prior Art
In a flat type fluorescent lamp of the conventional art, using no mercury therein, as shown in FIGS. 6(a) and (b), a pair of electrodes 102 and 103, each being coated with a dielectric material, are positioned within a sealed container, which is formed by hermetically bonding a transparent front substrate 100 and a rear substrate 101 together, wherein a fluorescent material is applied upon the inner surfaces of the front substrate 100 and the rear substrate 101, and Xe (xenon) gas is contained within the sealed container.
High voltage is applied between the electrodes 102 and 103 to cause dielectric barrier discharge, thereby atoms of the xenon gas, being excited or energized, irradiate ultraviolet rays therefrom. Receiving the ultraviolet rays, the fluorescent material, being of a three-color combination, converts the ultraviolet emission into visible light of red, green and blue colors, thereby achieving a function as a white color fluorescent lamp.
However, with such a flat type fluorescent lamp, the discharge occurs locally as opposed to uniformly if the distance between the electrodes is made large so as to obtain a large discharge area, therefore it is impossible to obtain a uniform fluorescence over the surface thereof. Because of this, for achieving a flat fluorescent lamp having large area, it is essential to newly devise the structure of the electrodes thereof.
Also, for the lamps having or using no mercury therein, a manner for increasing an efficiency of brightness comes to be a substantial challenge.
Further, the flat type fluorescent lamp, in particular, for use as a back light to be installed in a device such as a car navigation system, is required to be of high brightness, so that the display can be seen even in bright daylight surroundings, while it is required to be adjustable in the light amount emitted therefrom down to, for example, 3% of maximum radiation, in order to adjust for the greatly lesser light levels present inside of the car operated when driving during the night.